1. Field of the Invention
The present invention relates to an image pickup technology in which light-emitting elements produce an electronic flash light when picking up an image.
2. Description of the Related Art
A digital camera picks up an image of a subject by a photo detector such as a charge-coupled device (CCD). A CCD is provided with a photo diode that converts outdoor daylight into electric charges by the photoelectric effect. Charges generated according to the intensity of light record image information, i.e. performs imaging. A CCD itself is an element sensing the intensity of light and cannot capture color information of a subject image.
For this reason, a colored filter is usually provided for one CCD. For example, a color filter corresponds to, for example, a primary color such as red, green and blue (RGB). The color filter has the property of transmitting only the color it corresponds to. By combining CCDs and color filters, a digital camera is capable of capturing color information of a subject as well as the intensity of light.
In recent years, as the pixel resolution of a CCD is improved, many of battery-driven portable appliances such as portable telephones and personal data assistants (PDA) now have a built-in digital camera function. Many of these appliances use light-emitting diodes (LED) to provide backlight of a light-emitting device such as a liquid crystal display (LCD) and an electronic flash.
[Patent Document No. 1]
Japanese Laid-Open Patent Application No. 2002-116481